Electric furnace.



H. W. HIXON.

ELECTRIC FURNACE.

APPLICATION FILED JUNE 11, 1909.

e7 5 -E 5 n we E F W 5% =5 P E F i I OZ F "5 f g k 9/ z 3 LAZD INVENTOH HIHHM HIXUN ATTOHNE rs UNITED STATES PATENT OFFICE.

HIRAM WEISS HIXON, 0F PHILADELPHIA, PENNSYLVANIA.

ELECTRIC FURNACE;

To all whom it may concern:

Be it known that I, HIRAM WEISS I-Irxon, a citizen of the United States, residing at Philadelphia,in the county of Philadelphia and State of Pennsylvania, have invented an Improvement in Electric Furnaces, of which the following is a specification.

-My invention=relates to electric furnaces, more-particularly to. those furnaces used in the smelting of -zinc: ores and it consists. in the combinations, constructions and arrangements of parts herein described and claimed.

Hitherto the efforts to reduce zinc by electric smelting have been unsatisfactory owing to the production-of a blue powder in-.

stead of spelter. :One reason for the failure is that the -zinc vapor is obliged to rise against the cold charge-of ore which is fed in at-the top of the furnace;

An object of'm invention is to provide a device in which t e zinc is fed into the furnace, the top of which is kept closed so that the zinc vapor is forced: to escape at alower point, prefer-ably the taphole. To this end provide 'a furnace with a-top of double construction so that an 11 per door may be opened. and a charge fed in while the lower door is shut thereby keeping the zinc vapors within the furnace.

A further object of my-invention is to provide a'device in which there is a great increase-in the amount of ore handled per man employed, owing to the fact that the electric furnace can'be built to handle a much larger tonna than the ordinary retorts.

A' irther object of -my invention is to thoroughly volatilize the zinc from the fused material and also to heat the condenser above the boiling point of the zinc. This I obtain by meansof carbon electrodes 1nserted in the side of the condenser adjacent tothe top of the tap hole.

Otherobjects and advantages will appear in the following specification and the novel features of the device will be particularly pointedout in theap ended claims.

My invention is il ustrated in the accompanying drawing in which p Figure 1- shows a central vertical section throu h an electric zinc furnace constructed acco ing to'my invention, and Fig. 2 shows a horizontal section on a reduced scale throu h a portion of the furnace.

As eretofore stated one objection to the use of the ordinary electric furnace in zinc smelting is that the vapors of zinc arising Specification of Letters Patent.

Application filed June 11, 1909.

Patented May 10, 1910.

Serial No. 501,466.

from the smelting operation meet the cold charge coming in at the top of the furnace which resultsinthe formation of refractory compounds, of zinc to the detriment of the smelting operation. In order. to. overcome these obstacles, I have designed the form of furnaceshow-n in. Fig.1. ,This consists. of

a steel .shell A preferably of a cylindrical shapeand forming the inclosing casing of the furnace.- Vithinthe steel shell is a non-conducting ,refractpry lining B j which may be ofany appropriate dimensions and is preferably two or three feet thick. At the lower end of the furnace isfa ,layer G of therefractory. lining,upon which is a base or plate .D of carbon which is con nected to a source of electricity bymeans of a conductor ,d. Toward the topof the furnace is a similar plate ofcarbon E of an annular shape which is connected to the source of. electricity by means of the conductor e. The interior of the furnace may befilled with zinc ore to a point above the uppercarbon electrode E, the bottom ofithe chargeresting directly upon the lower elec trode D.. Y

In order to prevent the escape of any of the vapors I have arranged the double feeding hopper shown in Fig. 1.. This consists of. an upperfunnel like receptacleF. having a transverse shaft f extending therethrough' upon which a central .wheel 7 is located. At the bottomof the rece tacle F is a-closure f, of, a cone shaped orm, arrangedt'o fit snugly against the asbestos gaskets f disposed on lhe interior of the lower opening of the receptacle F. The closure is attached to the wheel f by means of the cable f. The shaft f is provided withthe crank handles f, f respectively.

The upper. hopper F projects down into and is supported by a lower hopper Gr having a similar shaft g, carrying the wheels 9 arranged to operate a closure g at the lower end of the receptacle G in a similar manner to the upper hopper. The lower hopper extends down into the interior 5 of the furnace.

At the, lower end of the furnace is the tap hole T which leads to the condenser K. This tap hole is smaller at the inside than at the outside as. shown in Fig. 1. Just above the tap hole I propose to locate a number of arcs R which are preferably connected in. parallel as Sl10\VIl lI1 Fig. 2. Immediately opposite the tap hole is an zinc ore and suflicient fine coal to reduce it, 7

is fed into the top of the furnace until. the furnace is full, both closures f and g being lowered to permit the free entrance of the charge. Owing to thepresence or the coal an electrical connection is established between the top electrode E and the bottomelectrode D. The current is now turned on and the heat developed in the charge by the resistance and the arcing of the current from piece to piece of the carbon in the charge roasts the charge. The tap hole is kept open to relieve the pressure of the accumulating gases and when the temperature has risen high enough to cause the reduction and volatilization of the zinc, the zinc vapor will begin to discharge into the condenser, and when it has reached a suficient density, it will condense to metallic zinc. The starting up of the ordinary zinc furnace always produces blue powder, until the vapor density of the zinc has reached a certain point, after which a the zinc continues to condense until by a reduction of zinc in the charge, the vapor density is reduced below the point required for the production of zinc, and from that point on, until the residues are discharged, blue owder forms again.

After the electric smelting furnace is once started there should be no let u in the vapor density as the furnace is fe continuously at the to and the hot zinc vapors are forced to discharge at the bottom by keeping the top of the furnace tightly closed. This is accomplished by means of the double charging hoppers already described. The hopper F is filled with a charge which by means of the handles f and f is delivered to the lower hopper G. The upper hopper F is then tightly closed by means of the closure i The charge is thus being heated in the lower hopper and when of the required temperature 1t is permitted to fall into the main portion of the furnace to take the place of the smelted product which is being drawn oii' from below. Thus it will be seen that there is no sudden change by a cold charge but that the vapor density of the zinc'will practically remain the same throughout the operation.

In Fi 1, I have shown a pocket or settler which orms part of the condenser and is adjacent the tap hole T. This is for the purpose of separatin and collectin the slag, residues and lea in the ore an this is provided with a constant dischar c 0r tap hole 8 for discharging the slag an resieaves? dues and lead, separated from the zinc. In order to kee, the zinc in a volatilized state so that itwiil be thoroughly separated from the fused material drawn out through the tap hole 8, I provide a series of arcs preferably in the form of carbon electrodes which project through the sides of the condenser, being immediately above the tap hole. The zinc vapor passes into the condenser and is then condensed in the usual manner and passes out through the outlet P. The progress of the operation may be observed through the observation hole 0.

With the furnace thus described it is possible to maintain the density of the zinc vapor at an ap roximately fixed point. This prevents the tormation of the blue powder and results in the continuous production of the metallic zinc.

While I have shown the electrodes as being in the form of carbon plates, it is obvious that. other forms might be used such as electrodes of graphite built into the walls of the furnace. The lining ofthe furnace might be of various non-conducting material such as lime, carborundum, magnesite or a C01 bination of the three in difi'erent layers rom the shell toward the interior.

Tclaim:

1. In an electric furnace for smelting zinc, a casing provided with a non-conducting refractory lining for receiving the charge, upper and lower electrodes arranged to contact with the charge and ada ted to connect with a source of current, 0 arging means arranged to operate so as to maintain the vapor density of the zinc in the furnace during the charging operation, means for separating the slag and means for condensing the zinc vapor.

2. In an electric furnace for smelting zinc, a hollow casing provided with a non-conducting lining arranged to receive a charge of ore, electrodes carried by said lining and arranged to contact with the charge, means for passing the current of electricity through the charge, a two compartment hopper carried by said casing for receiving and preheating the charge, independent means for opening and closing each compartmentof the hopper, and means for drawing off and condensing the zinc vapor.

3. In an electric furnace for smelting zinc, a hollow casing provided with a non-conducting lining arranged to receive a charge of ore, electrodes carried b said lining and arranged to contact with t e charge, means for passing a current of electricity through the charge, a two compartment hopper carried by said casing for receiving the charge, independent means for opening and closing each compartment of the hopper, said means comprising a shaft, a wheel upon said shaft, and a cone shaped closure arran ed to be drawn up into engagement with t e moutht l l furnace, a tap hole at the bottom of said furnace, an exterior condenser communicating with said tap hole, and means for producing a series of electric arcs immediately above the tap hole for maintaining the zinc vapor in a gaseous condition while passing into the condenser.

HIRAM WEISS HIXON. Witnesses A. A. LOGAN, MARY E. LOGAN. 

